Flag passed to the driver indicating which interface is open. Valid settings are:

OTYP_BLK

Open the device block interface.

OTYP_CHR

Open the device character interface.

Only one OTYP flag can be specified. To open streams devices, specify OTYP_CHR.

flag

Bit field that instructs the driver on how to open the device. Valid settings are:

FEXCL

Open the device with exclusive access; fail all other attempts to open the device.

FNDELAY

Open the device and return immediately. Do not block the open even if something is wrong.

FREAD

Open the device with read-only permission. (If ORed with FWRITE, allow both read and write access).

FWRITE

Open a device with write-only permission (if ORed with FREAD, then allow both read and write access).

FNOCTTY

Open the device. If the device is a tty, do not attempt to open it as a session-controlling tty.

Description

The ldi_open_by_dev(), ldi_open_by_name() and ldi_open_by_devid() functions allow a caller to open a
block, character, or streams device. Upon a successful open, a layered handle
to the device is returned via the layered handle pointed to by lhp.
The ldi identifier passed to these functions is previously allocated with ldi_ident_from_stream(9F),
ldi_ident_from_dev(9F), and ldi_ident_from_dip(9F).

The ldi_open_by_dev() function opens a device specified by the dev_t pointed to
by devp. Upon successful open, the caller should check the value
of the dev_t to see if it has changed. (Cloning devices will
change this value during opens.) When opening a streams device, otyp
must be OTYP_CHR.

The ldi_open_by_devid() function opens a device by devid. The caller must specify
the minor node name to open.

The ldi_open_by_name() function opens a device by pathname. Pathname is a null
terminated string in the kernel address space. Pathname must be an absolute
path, meaning that it must begin with '/'. The format of the
pathname supplied to this function is either a /devices path or any
other filesystem path to a device node. Opens utilizing /devices paths are
supported before root is mounted. Opens utilizing other filesystem paths to device
nodes are supported only if root is already mounted.

The ldi_close() function closes a layered handle that was obtained with either
ldi_open_by_dev(), ldi_open_by_name(), or ldi_open_by_devid(). After ldi_close() returns the layered handle, the lh
that was previously passed in is no longer valid.

Return Values

The ldi_close() function returns 0 for success. EINVAL is returned for invalid
input parameters. Otherwise, any other error number may be returned by the
device.

The ldi_open_by_dev() and ldi_open_by_devid() functions return 0 upon success. If a failure
occurs before the device is open, possible return values are shown below.
Otherwise any other error number may be returned by the device.

EINVAL

Invalid input parameters.

ENODEV

Requested device does not exist.

ENXIO

Unsupported device operation or access mode.

The ldi_open_by_name() function returns 0 upon success. If a failure occurs before
the device is open, possible return values are shown below. Otherwise any
other error number may be returned by the device.

EINVAL

Invalid input parameters.

ENODEV

Requested device path does not exist.

EACCES

Search permission is denied on a component of the path prefix, or the file exists and the permissions specified by cr are denied.

ENXIO

Unsupported device operation or access mode.

Context

These functions may be called from user or kernel context.

These functions should not be called from a device's attach, detach, or
power entry point. This could result in a system crash or deadlock.

See Also

Notes

Use only OTYP_CHR or OTYP_BLK options when you use the ldi_open_by_dev() and
ldi_open_by_devid() functions to open a device. Other flags, including OTYP_LYR, have been
deprecated and should not be used with these interfaces.

The caller should be aware of cases when multiple paths to a
single device may exist. (This can occur for scsi disk devices
if scsi_vhci(7D)) is disabled or a disk is connected to multiple controllers not
supported by scsi_vhci(7D).

In these cases, ldi_open_by_devid() returns a device handle that corresponds to a
particular path to a target device. This path may not be
the same across multiple calls to ldi_open_by_devid(). Device handles associated
with the same device but different access paths should have different filesystem device
paths and dev_t values.

In the cases where multiple paths to a device exist and access
to the device has not been virtualized via MPXIO (as with scsi
disk devices not accessed via scsi_vhci(7D)), the LDI does not provide any
path fail-over capabilities. If the caller wishes to do their own path
management and failover they should open all available paths to a device
via ldi_open_by_name().